Identification Pacejka tyre model
Identification Pacejka tyre model
(OP)
Hi all,
I need to derive the Pacejka data of a tyre installed on a commercial vehicle to perform a multibody simulation of the vehicle. I performed the ISO steady state test. The commercial vehicle doesn't have any rear suspension and also it's top speed is of 60 km/h. The steady state behaviour is almost linear in the whole range. The maximum lateral acceleration is 0.4g. I try to derive Pacejka's coefficient through the bycicle model. Is it a good idea?
thanks
Pietro
I need to derive the Pacejka data of a tyre installed on a commercial vehicle to perform a multibody simulation of the vehicle. I performed the ISO steady state test. The commercial vehicle doesn't have any rear suspension and also it's top speed is of 60 km/h. The steady state behaviour is almost linear in the whole range. The maximum lateral acceleration is 0.4g. I try to derive Pacejka's coefficient through the bycicle model. Is it a good idea?
thanks
Pietro





RE: Identification Pacejka tyre model
However, you probably need to set all the non linear scaling functions to sensible values, as the data you have won't help much with them.
If your only concern is linear range then a simpler tire model might be easier to work with.
As an example of the problems you face, you probably don't have a good idea of load sensitivity or camber effects from your test.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Identification Pacejka tyre model
thanks for your reply. I performed the steady state test in different loading condtions and trends are linear only for the unladen vehicle. For the full loaded one, front tyres are almost saturated. Yesterday I tried and the fit is pretty good in all conditions. I will try with the full vehicle model and check the differences in both methods and try to identificate tyres parameters. Moreover if the parameteres are normalized to the vertical load, should I get the same parameters for each wheel in different vehicle conditions, right?
Thanks
Pietro
RE: Identification Pacejka tyre model
The normal way of fitting a Pac model is to use ALL your data in one almighty matrix, not to try and fit at just one load and adjust it.
What procedure or program are you using to fit the data?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Identification Pacejka tyre model
thanks for your reply. I'm sorry for the silly question, I know it, I wanted to edit the post immedialy but it wasn't possible. I used matlab curve fitting toolbox. I fitted data for each loading condition due to the load sensitivity effect, but I normalized each coefficient with the tractor static load. Is it the right way?
Thanks
Pietro
RE: Identification Pacejka tyre model
So, roughly, I have a spreadsheet of Fz alpha gamma Fy Mx Mz PacFy PacMx PacMz where the pac columns are calculated from my current Pac coefficients. (I don't actually do this, but conceptually this is the approach).
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Identification Pacejka tyre model
thanks for your reply. Why isn't it better to fit the data for each loading condition separately? Since they are load sensitive, I thought it would be better. I'm sorry if I miss something.
Cheers
Michele
RE: Identification Pacejka tyre model
It would be interesting to do it both ways and compare the results.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Identification Pacejka tyre model
Thanks
Cheers
Pietro